1. Fields of the Invention
The present invention relates to a wrench, and more particularly, to a wrench suitable for operating objects of different sizes.
2. Descriptions of Related Art
U.S. Pat. No. 4,967,612 discloses a flare nut wrench and comprises a resilient socket having an internal surface defining an area for receiving a flare nut. The internal surface is used for gripping engagement with the external surface of a flare nut. The socket has an outer socket face and has a gap therein through which a tube secured by the flare nut passes prior to engaging the socket with the flare nut. A base has an axial line extending therethrough, and a socket pivot on the base is positioned on one side of the axial line for pivoting the socket with respect to the base. A prong projects from the base on the other side of the axial line at a location spaced laterally of the socket pivot. The prong has a prong surface extending in the general direction of the axial line for engagement with the outer face of the socket. The gap extends totally between the prong and the socket pivot when the outer socket face is engaged by said prong. The gap extends for a selected circumferential distance such that it remains open upon engagement of the socket with the flare nut and prong. A handle means is associated with the base for applying torque to the wrench to rotate the flare nut. The handle means urges the prong surface against the outer face of the socket to squeeze the socket against the external surface of the flare nut so as to prevent the gap from opening and to thereby prevent the wrench from rounding off the flare nut.
However, the socket has to contact the consecutive sides of the object to rotate the object, and after the wrench is rotated an angle, the socket has to be disengaged from the object and re-mount to the object at another angle, this prolongs operation time. Besides, only one side of the object can be rotated by the wrench.
U.S. Pat. No. 6,978,701 discloses a wrench having a head portion adapted to engage and apply torque to a workpiece, and turning means for turning the head portion. The wrench further comprises a flexible ring portion included in the head portion and attached to the turning means at one end and free at its other end. The ring portion has an inner working surface for engaging the workpiece. A clamping means is included in the turning means for clamping the free end of the ring portion against the workpiece when the turning means is turned in a predetermined direction. A portion of the flexible ring portion at or adjacent the free end thereof has an external, first cam surface which defines a wedge shape with the inner working surface of the portion. The wedge shape increases in thickness towards the free end of the flexible ring portion. The clamping means has a second cam surface arranged to cooperate with said wedge-shaped portion so that when torque is applied to the head portion in the predetermined direction, the wedge-shaped portion is urged in such a peripheral direction relative to the workpiece as to tend to close the flexible ring portion around the workpiece.
The wrench can only rotate a fixed sized workpiece and the structure require multiple steps of welding processes and which increase the manufacturing cost. When operating, the pivotal paths are difficult to be controlled due to the complicated pivoting connections.
The present invention intends to provide a wrench which is designed to improve the shortcomings mentioned above.